String和InputStream、Reader 的转换

1、

     String --> InputStream ：

     InputStrem is = new ByteArrayInputStream(str.getBytes());

     or

     ByteArrayInputStream stream = new ByteArrayInputStream(str.getBytes());

2、

    InputStream-->String 

     BufferedReader in = new BufferedReader(new InputStreamReader(is));

     StringBuffer buffer = new StringBuffer();

     String line = "";

     while ((line = in.readLine()) != null){

         buffer.append(line);

     }

     return buffer.toString();

3、

     String-->Reader

     Reader reader = null;

     BufferedReader r = new BufferedReader(reader);

     StringBuilder b = new StringBuilder();

     String line;

     while((line=r.readLine())!=null) {

         b.append(line);

         b.append("\r\n");

     } 

     b.toString();